Developer API · 40,979 ZIP codes

ZIP Code API, priced for a side project

Query a US ZIP code from your own server and get city, state, county and coordinates back as JSON. $9 per month for 1,000 requests. When the limit is reached the API stops; it does not silently bill an overage.

Get an API key Try the free lookup

Endpoint

GET

https://addresstool.org/api/v1/zip?q=90210

Header: x-api-key: YOUR_KEY

Example

curl "https://addresstool.org/api/v1/zip?q=90210" \
  -H "x-api-key: YOUR_KEY"

{
  "query": "90210",
  "count": 1,
  "results": [{
    "zip": "90210",
    "city": "Beverly Hills",
    "state": "CA",
    "county": "Los Angeles",
    "latitude": 34.0901,
    "longitude": -118.4065
  }],
  "quota": {
    "plan": "starter",
    "used": 1,
    "limit": 1000,
    "remaining": 999
  }
}

Status codes

401 missing or invalid key.
429 monthly limit reached; the counter resets on the 1st (UTC).
503 ZIP database temporarily unavailable. Retry with backoff.

Questions

How much does the ZIP API cost?+

The Starter plan is $9 per month for 1,000 requests. When the counter reaches 1,000, requests return HTTP 429 until the next UTC month. There is no automatic overage charge.

What does a response contain?+

ZIP code, city, state, county, latitude and longitude. A query can be a five-digit ZIP, a two-letter state code, or a city prefix.

How do I get a key?+

Subscribe with a card on this page. The key appears after the payment is verified and the quota resets on the 1st of each UTC month. Keep the key in a secret manager; we store only its SHA-256 hash.

Is the ZIP data live USPS data?+

No. It is a GeoNames-derived dataset of 40,979 ZIP codes for lookup and form testing. It is not a USPS delivery validation service and does not certify that an address is mailable.